Metabolic fate of leucine: Considering that leucine is a strictly ketogenic amino acid, what is a principal end product of its catabolism?

Introduction / Context:
Amino acids are categorized as glucogenic, ketogenic, or both based on the metabolic products they yield. Leucine is the prototypical strictly ketogenic amino acid, important in muscle metabolism and signaling via mTOR.

Given Data / Assumptions:

• Leucine catabolism generates acetyl-CoA and acetoacetate but not net glucose precursors.
• Question asks for a principal end product among provided options.

Concept / Approach:
Ketogenic amino acids degrade to acetyl-CoA or acetoacetate, feeding ketone body synthesis or the TCA cycle for energy without net gluconeogenesis (since acetyl-CoA carbons are lost as CO2 in TCA).

Step-by-Step Solution:
Recall leucine pathway: transamination → oxidative decarboxylation → ultimately acetyl-CoA + acetoacetate.Compare options: only acetyl-CoA matches a canonical leucine end product listed.Select ‘‘Acetyl-CoA.’’

Verification / Alternative check:
Biochemical charts show leucine as purely ketogenic alongside lysine; both feed acetyl-CoA/acetoacetate pools.

Why Other Options Are Wrong:

• Pyruvate and oxaloacetate are glucogenic entry points; leucine does not yield these.
• Acetyl carnitine is a transport/storage form derived from acetyl-CoA and carnitine, not the primary metabolic end product itself.

Common Pitfalls:
Assuming all amino acids can be converted to glucose; overlooking that acetyl-CoA carbons cannot contribute net to gluconeogenesis.

Final Answer:
Acetyl-CoA